1. Field of the Invention
The present invention relates generally to medical devices and more specifically, to an introducer having a hemostatic valve system for use in inserting a medical device into a body vessel.
2. Background
Numerous procedures have been developed in modern medicine requiring the percutaneous insertion of one or more medical devices into the vascular system of a patient. Such procedures include, for example, percutaneous transluminal coronary angioplasty (PTCA), X-ray angiographic procedures, and the alike.
The medical devices intended for use in such procedures may be introduced into the vascular system by a variety of known techniques. One widely-used technique is the Seldinger technique. In the Seldinger technique, a surgical opening is made in an artery or vein by a needle, and a guide wire is inserted into the artery or vein through a bore in the needle. The needle is thereafter withdrawn, leaving the guide wire in place. A dilator which is positioned within the lumen of the introducer device is then advanced over the guide wire into the artery or vein. Once the introducer is properly positioned within the artery or vein, the dilator is withdrawn. The introducer may then be used to insert therethrough a variety of medical interventional devices, such as for example, catheters, cardiac leads, and the alike.
In many cases, an introducer will include one or more hemostatic valve members (also referred to as check valves) for inhibiting leakage of body fluids, such as blood, back through the introducer as a medical device is inserted or withdrawn therethrough. The medical device may be for example, the dilator, a medical interventional device, e.g., catheter, or the alike. The valve member is generally positioned in a housing of the introducer, between a main body portion and an end cap. Typically, the valve member comprises an elastomeric disk having a hole formed therethrough in the center of the disk. The hole is sized to enable the medical device to be passed through the valve member, and to substantially prevent the back flow of fluids through the valve. Hemostatic valves are well known in the medical art for such purpose, and no further general discussion of the use and function of such valves is necessary for an understanding of the present invention.
Frequently, it is necessary to withdraw an inserted medical device and/or replace it with another medical device of a different diameter, or with a different type of device. In the case of replacing a previously inserted device, exchanges are normally made over a guide wire, where the old device is withdrawn over the guide wire, and the new device is thereafter inserted into the vasculature over the existing guide wire or a newly-inserted guide wire. Typically, the hemostatic valve is provided in an attempt to minimize leakage of blood back through the introducer. Such valves are dependent upon the elasticity of the valve body, and its ability to draw back upon itself to seal any gap created upon insertion or withdrawal of a device through the valve. However, the valve bodies do not always reset (e.g. due to plastic deformation of the valve body) in the proper manner following passage of the medical device and thus, additional gaps through which fluid may bleed may be created. For example, when one or more disks having a hole formed through the center are used, the hole may only partially retract back to its original size following the removal of a larger diameter catheter or other medical device. As a result, the now expanded center hole may allow substantial leakage of body fluids. Such valves may be satisfactory when there is no need to remove a device that seals the opening, however, they may be problematic when the device is removed and the center opening is created and/or enlarged.
Moreover, when larger hole opening valves are utilized, the medical device may tear the valve disk beyond the hole upon insertion. This is particularly true when a larger sized medical device is inserted. In such cases, multiple valve disks may be incorporated in order to provide a reasonable degree of confidence that the valve system will continue to provide at least some leakage control. In some cases, the damage to the valve may be so severe that it will be necessary to incorporate another type of valve, such as a Tuohy-Borst type valve, into the introducer.
Similarly, when smaller hole opening valves are utilized, the valves are also subject to tearing even when smaller sized medical devices are passed therethrough. Also, small size interventional devices are often delicate, and posses little hoop strength. When such devices are passed through a small valve member, the thickness and strength of the valve member may cause damage to the delicate structure upon passage therethrough of the medical device. Moreover, when small disks are used, the clearance between the openings and the disk in the medical device can be so slight that it may be difficult to insert and or withdraw the medical device. On some occasions, additional small diameter tubing may be used to keep the valve open so that a catheter or other medical device may be passed therethrough. When additional equipment is required, such as a small diameter tube or a Tuohy-Borst valve as described, the surgeon's hands and attention may be unduly distracted at the very time when all possible focus should be on the major task at hand.
Accordingly, further improvements and enhancements are needed for an introducer that includes a hemostatic valve system, which provides an efficient seal and avoids at least some of the problems encountered with current art seals.